perf(gsi): add index on (base_pk, base_sk_*) for cascade deletes#116
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perf(gsi): add index on (base_pk, base_sk_*) for cascade deletes#116parsnips wants to merge 1 commit into
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Cascade-delete from base-table writes runs `DELETE FROM <gsi> WHERE base_pk = $1 [AND base_sk_<type> = $n ...]` against every GSI table. Neither the PK constraint nor the existing ordering index can serve this lookup because both lead with `pk`, so PostgreSQL falls back to a Seq Scan. In a recent benchmark this missing index accounted for ~74% of total DB time. Create an index that mirrors the cascade-delete predicate at GSI table creation time. Column order matches the PK constraint minus the leading `pk`, so for a single-bytes base SK this produces `(base_pk, base_sk_b)`. The index is created unconditionally — HASH-only base tables still benefit from `(base_pk)` alone. Only applies to GSI tables created after this change; existing deployments need a backfill migration to pick up the index. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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looks like #127 will fix this. |
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What
Cascade-delete from base-table writes runs
DELETE FROM <gsi> WHERE base_pk = $1 [AND base_sk_<type> = $n ...]against every GSI table. Neither the PK constraint nor the existing ordering index can serve this lookup because both lead withpk, so PostgreSQL falls back to a Seq Scan. In a recent benchmark this missing index accounted for ~74% of total DB time.Create an index that mirrors the cascade-delete predicate at GSI table creation time. Column order matches the PK constraint minus the leading
pk, so for a single-bytes base SK this produces(base_pk, base_sk_b). The index is created unconditionally — HASH-only base tables still benefit from(base_pk)alone.Only applies to GSI tables created after this change; existing deployments need a backfill migration to pick up the index.
Why
GSI Ops should be fast.
Closes #115
Testing done
Manually applied and ran an internal benchmark and plan.
Checklist
cargo test --workspace)cargo fmt --check)cargo clippy -- -W clippy::pedantic)By submitting this pull request, I confirm that my contribution is made under
the terms of the Apache License 2.0 and I agree to the Developer Certificate of
Origin (DCO). See CONTRIBUTING.md for details.